US3867512A - Method of preparing crystalline {37 l{38 {0 zeolite - Google Patents
Method of preparing crystalline {37 l{38 {0 zeolite Download PDFInfo
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- US3867512A US3867512A US289085A US28908572A US3867512A US 3867512 A US3867512 A US 3867512A US 289085 A US289085 A US 289085A US 28908572 A US28908572 A US 28908572A US 3867512 A US3867512 A US 3867512A
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- silica
- zeolite
- sio2
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- gelling
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- 239000010457 zeolite Substances 0.000 title claims abstract description 17
- 229910021536 Zeolite Inorganic materials 0.000 title claims abstract description 16
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 title claims abstract description 16
- 238000000034 method Methods 0.000 title claims description 21
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 111
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 47
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 39
- 239000000126 substance Substances 0.000 claims abstract description 24
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 15
- 239000002253 acid Substances 0.000 claims description 11
- 239000000741 silica gel Substances 0.000 claims description 11
- 229910002027 silica gel Inorganic materials 0.000 claims description 11
- 239000011541 reaction mixture Substances 0.000 claims description 9
- 235000012239 silicon dioxide Nutrition 0.000 claims description 9
- 239000000203 mixture Substances 0.000 claims description 8
- 238000002360 preparation method Methods 0.000 claims description 8
- -1 AMMONIUM SILICATES Chemical class 0.000 claims description 7
- 230000000875 corresponding effect Effects 0.000 claims description 6
- 229910052783 alkali metal Inorganic materials 0.000 claims description 4
- 239000007864 aqueous solution Substances 0.000 claims description 4
- 229910052500 inorganic mineral Inorganic materials 0.000 claims description 4
- 239000011707 mineral Substances 0.000 claims description 4
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical group C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims description 3
- 150000001340 alkali metals Chemical class 0.000 claims description 3
- 230000015572 biosynthetic process Effects 0.000 claims description 3
- 230000002596 correlated effect Effects 0.000 claims description 3
- 239000011734 sodium Substances 0.000 claims description 3
- 229910052708 sodium Inorganic materials 0.000 claims description 3
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims description 2
- 150000001342 alkaline earth metals Chemical class 0.000 claims description 2
- 239000003153 chemical reaction reagent Substances 0.000 claims description 2
- 239000012141 concentrate Substances 0.000 claims description 2
- 229910052681 coesite Inorganic materials 0.000 claims 3
- 229910052906 cristobalite Inorganic materials 0.000 claims 3
- 229910052682 stishovite Inorganic materials 0.000 claims 3
- 229910052905 tridymite Inorganic materials 0.000 claims 3
- KKCBUQHMOMHUOY-UHFFFAOYSA-N Na2O Inorganic materials [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 claims 2
- WPUINVXKIPAAHK-UHFFFAOYSA-N aluminum;potassium;oxygen(2-) Chemical group [O-2].[O-2].[Al+3].[K+] WPUINVXKIPAAHK-UHFFFAOYSA-N 0.000 claims 1
- 229910052593 corundum Inorganic materials 0.000 claims 1
- LRCFXGAMWKDGLA-UHFFFAOYSA-N dioxosilane;hydrate Chemical compound O.O=[Si]=O LRCFXGAMWKDGLA-UHFFFAOYSA-N 0.000 claims 1
- 235000019353 potassium silicate Nutrition 0.000 claims 1
- 235000019351 sodium silicates Nutrition 0.000 claims 1
- 229910001845 yogo sapphire Inorganic materials 0.000 claims 1
- 239000000499 gel Substances 0.000 abstract description 38
- 239000000243 solution Substances 0.000 description 10
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 8
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 6
- 239000004115 Sodium Silicate Substances 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 6
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 6
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 6
- 229910052911 sodium silicate Inorganic materials 0.000 description 6
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 5
- 239000000908 ammonium hydroxide Substances 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- 229910000323 aluminium silicate Inorganic materials 0.000 description 4
- 238000001354 calcination Methods 0.000 description 4
- 238000001035 drying Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- KVOIJEARBNBHHP-UHFFFAOYSA-N potassium;oxido(oxo)alumane Chemical compound [K+].[O-][Al]=O KVOIJEARBNBHHP-UHFFFAOYSA-N 0.000 description 4
- 239000000376 reactant Substances 0.000 description 4
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000008131 herbal destillate Substances 0.000 description 3
- 230000009257 reactivity Effects 0.000 description 3
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical group [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- 150000007513 acids Chemical class 0.000 description 2
- 239000004964 aerogel Substances 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 239000012736 aqueous medium Substances 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 239000000084 colloidal system Substances 0.000 description 2
- 238000001879 gelation Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000012429 reaction media Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000012690 zeolite precursor Substances 0.000 description 2
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- 239000005995 Aluminium silicate Substances 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- KRKNYBCHXYNGOX-UHFFFAOYSA-K Citrate Chemical compound [O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O KRKNYBCHXYNGOX-UHFFFAOYSA-K 0.000 description 1
- BDAGIHXWWSANSR-UHFFFAOYSA-M Formate Chemical compound [O-]C=O BDAGIHXWWSANSR-UHFFFAOYSA-M 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 229910001854 alkali hydroxide Inorganic materials 0.000 description 1
- 229910001860 alkaline earth metal hydroxide Inorganic materials 0.000 description 1
- 235000012211 aluminium silicate Nutrition 0.000 description 1
- ANBBXQWFNXMHLD-UHFFFAOYSA-N aluminum;sodium;oxygen(2-) Chemical compound [O-2].[O-2].[Na+].[Al+3] ANBBXQWFNXMHLD-UHFFFAOYSA-N 0.000 description 1
- 239000008346 aqueous phase Substances 0.000 description 1
- 239000012431 aqueous reaction media Substances 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- FDNDTQWNRFFYPE-UHFFFAOYSA-N carbonic acid;nitric acid Chemical compound OC(O)=O.O[N+]([O-])=O FDNDTQWNRFFYPE-UHFFFAOYSA-N 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000029087 digestion Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 239000003517 fume Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 150000004820 halides Chemical class 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- 235000005985 organic acids Nutrition 0.000 description 1
- 230000020477 pH reduction Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 235000011007 phosphoric acid Nutrition 0.000 description 1
- 150000003016 phosphoric acids Chemical class 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 159000000001 potassium salts Chemical class 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 230000001698 pyrogenic effect Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 150000004760 silicates Chemical class 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 229910001388 sodium aluminate Inorganic materials 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 239000006228 supernatant Substances 0.000 description 1
- 238000007669 thermal treatment Methods 0.000 description 1
- 150000004684 trihydrates Chemical class 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 230000004580 weight loss Effects 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B39/00—Compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites; Their preparation; After-treatment, e.g. ion-exchange or dealumination
- C01B39/02—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof
- C01B39/32—Type L
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S423/00—Chemistry of inorganic compounds
- Y10S423/28—LTL, e.g. BA-G, L, AG-1, AG-2, AG-4, BA-6
Definitions
- ABSTRACT Crystalline zeolite L is prepared in high yields from reactive silica gels having chemical water contents in excess of about 4.5 weight percent.
- the reactive silicas are preferably prepared by gelling a selected silica source at a pH below about 5.
- silica having very high surface areas usually attributable to minute particle sizes, such as the fume silicas, pyrogenic silicas and precipitated silica sols are more readily converted to certain zeolites than are alternative silica sources.
- one object of this invention to provide a method for the preparation of zeolite-L. It is another object of this invention to provide a method for the preparation of zeolite-L from inexpensive readily available silica sources. It is yet another object of this invention to provide a method for the preparation of zeolite L which enables the more economic utilization of zeolite precursors. Another object is to improve conversion of reactants to crystalline zeolite-L.
- crystalline zeolite-L is produced by reacting a silica gel having a chemical water content above about 4.5 weight percent with a source of alumina in an aqueous reaction medium having a composition expressed as oxide mole ratios of about 0.3 to about 1 K O/(K O Na O), about 0.3 to about 0.6 (K O+Na O)/SiO about to about 40 SiO /Al O and about to about 140 H O/(K O-FNa O), at a temperature and for a period of time sufficient to form crystalline zeolite-L.
- L-zeolite is formed in high yields by the reaction of an alumina source and a reactive silica gel formed by syneresis at a temperature above about 100? and a pH below about 8 sufficient to produce a gel having a chemical water content of at least about 4.5 weight percent. Even higher tempera tures on the order of 150F and above are preferred in this embodiment.
- Such reactive silicagels can be prepared at temperatures of about 30 to about 250F and pH levels below about 8. Higher temperatures can be used if facility is provided for'maintaining pressure on the system. For convenience, temperatures below 250F are usually employed. However, suitable gels cannot be prepared at the higher pH levels and lower temperatures. Thus it is necessary to correlate the temperature and pH level at which the gel is produced in order to assure the resulting product will have a chemical water content of at least about 4.5 weight percenLHowever, silica gels having this characteristic can be prepared throughout this temperature range at the lower pH levels, i.e., below about 5, preferably below about 3.
- This method is based on the discovery that silica gels containing at least about 4.5 weight percent water react with alumina sources to form zeolite-L much more readily and with higher efficiency than do other silicas.
- the silica gels formed at low pH below about 5 are presently preferred due to their superior activity in these systems.
- the superiority of these gels is unexpected since they are not superior Y zeolite precursors.
- the use of low pH gels having high water levels often results in the production of no Y zeolite whatever.
- the results obtained with zeolite Y suggest that if any difference in reactivity or conversion level exists between the numerous alternative silica sources, it is that silicas prepared in less acidic media are more reactive. I have now discovered that, to the contrary, silica gels having high chemical water levels, and preferably those prepared in more acidic media, or alternatively at higher temperatures, are much more reactive for the formation of zeolite-L in the systems described herein.
- the reactive silica gel, as formed, should have a relatively high chemical water content of at least about 4.5 weight percent.
- Such gels are much more reactive for the production of L zeolite than are available alternatives formed under conditions which result in lower chemical water levels. They are usually prepared at pH levels below about 8 under conditions sufficient to produce a producthaving a chemical water content in excess ofabout 4.5 weight percent.
- Gelling temperature has a significant influence on chemical water content. Higher chemical water levels are obtained at higher temperatures. Similarly, chemical water level increases as the gelling pH is reduced. Thus, temperature and pH must be correlated to obtain a reactive silica.
- T is the gelling temperature in degrees Rakine.
- Other variables such as silica concentration effect the validity of this expression somewhat. Nevertheless, it does provide a means for correlating temperature and pH as a preliminary step to establishing optimum reaction conditions.
- the optimum conditions of temperature, pH and silica content can be easily determined experimentally by producing gels at several pH levels, temperatures and silica concentrations, determining the resultant chemical water content of the gel, and selecting the optimum conditions accordingly.
- a simple procedure for determining chemical water content involves drying the gel at 110C for 16 hours to expel physically bound water and then determining weight loss of the dried gel upon heating at l,lC for 2 hours.
- a variety of gel precursors can be employed to produce these materials. Exemplary of these are the alkali metal, alkaline earth metal and ammonium silicates and silicic acid.
- Silica concentration should correspond to a Si0,lH O mole ratio of at least about 0.005 in order to produce a relatively concentrated gel which can be easily separated from the aqueous phase. Lower silica concentration can be employed although they are not preferred due to handling difficulty and the need for unfeasibly long contact times. Somewhat higher equivalent SiO /H O ratios within a range of about 0.01 to about 0.1 are generally employed, the higher concentrations being preferred due to ease in handling and shorter gelling times.
- An alternative procedure involves the acidification of a basic silicate or silicic acid in an aqueous medium at a pH of about 0 and then increasing the pH to a value in excess of about 5, and preferably less than about 3.
- the solution pH will raise slightly due to the neutralizing effect of the basic silicate.
- additional base can be added such as ammonium or alkali and alkaline earth metal hydroxides, carbonates and the like.
- any acid which will neutralize the basic silicate can be employed in this step of the procedure.
- illustrative acids are the strong mineral acids such as sulfuric, hydrochloric, nitric and phosphoric and organic acids such as formic, acetic and the like.
- the silica gel is separated from the supernatant liquid and water washed to remove residual acid.
- the resulting gel can be employed directly in the preparation of the aluminosilicates hereinafter detailed with or without mild drying or calcination.
- additional improvement in the suitability of these gels as reactants in the production of zeolite-L can be achieved by calcination prior to contacting in the aluminosilicate reaction medium.
- calcination is not essential due to the enhanced activity of these materials post treatment at temperatures of about 400 to about l,800F, preferably above about 600F for about 30 minutes to about 2 hours serves to further increase reactivity. Obviously such thermal treatment will reduce the gel water content.
- the resulting silica source is contacted with a suitable alumina source in an aqueous medium having a composition expressed as oxide mole ratios of about 15 to about H O/( K O+Na O) from about 0.3 to about 0.6 (K O+Na O)/SiO from about 10 to about 40 SiO /AI O It has also been found that the presence of minor amounts of sodium in the metalaluminosilicate reaction mixture expedites the production of zeolite L particularly in the potassium form.
- alumina trihydrate activated alumina
- alkali metal aluminates e.g., sodium aluminate, potassium aluminate, etc.
- gamma alumina alumina containing clays such as kaolin and the like
- potassium aluminate being presently preferred.
- the required potassium concentration can be derived from potassium hydroxide or one or more ionizable potassium salts such as the sulfate, halides, nitrate carbonate, acetate, formate, citrate and the like.
- the zeolite-L is prepared by dispersing the alumina, alkali and silica sources in water under any of a wide range of conditions. Reaction temperatures can range from 140 to about 280F. although temperatures of about 180 to 230F. are generally preferred due to reaction rate and system vapor pressure. Product crystals can be separated from the reaction medium by any suitable method such as filtration. Purification is easily accomplished by water washing and mild drying if preferred. Contact times are usually at least about 30 minutes and are generally within the range of about 1 to about 48 hours.
- EXAMPLE 1 A 1050 ml portion of N-Brand" sodium silicate was diluted with 4000 ml of water to form a solution which was then added to 380 ml of 12 normal sulfuric acid. Immediately following admixture of the silicate and acid solutions, the pH was adjusted to 4.0 by the addition of normal ammonium hydroxide. The resulting system was allowed to stand for minutes at 75F. at which time the first signs of gelation became apparent. At that time, i.e., after 30 minutes, sufficient additional ammonium hydroxide was added to the system to increase the pH to 9.0, whereupon the system set into a firm gel. The resulting gel was water washed to remove acid and soluble salts and dried for 16 hours at 2l2F. The dried gel was then ground into particulate form through a 0.0l0-slotted screen.
- EXAMPLE 2 A 2 I00 ml portion ofN-Brand sodium silicate was diluted with 8000 ml of water. The resulting solution was then added to an excess of sulfuric acid, 702 ml of 12 normal H 50 Immediately following the combina- EXAMPLES 5-9 These silicas and a sample of Ludox-HS silica sol were separately mixed with potassium aluminate and water in amounts sufficient to form a metalaluminosilicate reaction mixture having the following composition represented as oxide mole ratios: H O/K O 90; K- O/SiO 0.40; SiO /Al O 20. The slurries were aged in a pressure vessel under system vapor pressure at 240F for 68 hours.
- EXAMPLE 3 A 755 ml portion of N-Brand" sodium silicate was admixed with 970 ml of water to form a solution which was then added gradually to 432 ml of 12 normal sulfuric acid. The original pH of the solution was 0. However, after star ding for 48 hours to enable the system EXAMPLES l0-l 5 Six additional L-zeolite preparations were made using the procedures described above. The conditions employed and results obtained are illustrated in the following Table.
- EXAMPLE 4 A 2100 ml portion ofN-Brand sodium silicate was diluted with 8400 ml of water and added gradually to 702 ml of 12 normal sulfuric acid. Immediately following the combination of the silicate and acid solutions the pH of the system was adjusted to 7.0 by the addition 1.
- aqueous reaction mixture having a molar composition corresponding to about 0.3 to about 1 K O/(K O-l-Na O), about 0.3 to 0.6 (K O+Na O)/- SiO about l0 to 40 SiO /AI O and about l5 to I40 H O/(K O+Na O), and wherein said reaction mixture is digested at a temperature and for a period of time sufficient to produce a recoverable yield of zeolite L,
- the improved method for increasing the rate of formation and/or yield of L zeolite which comprises utilizing as said reactive silica a reactive silica gel prepare by gelling a silica source selected from the group consisting of alkali metal, akaline earth metal and ammonium silicates and silicic acid in an aqueous solution having a silica concentrate corresponding to a SiO /H O mole ratio of at least about 0.005 at a pH below about 8 and a temperature between about 30 and 250F, correlated with said pH to produce a reactive silica gel containing at least about 4.5 weight percent of chemical water.
- a silica source selected from the group consisting of alkali metal, akaline earth metal and ammonium silicates and silicic acid
- a silica concentrate corresponding to a SiO /H O mole ratio of at least about 0.005 at a pH below about 8 and a temperature between about 30 and 250F
- said reactive silica gel is formed by gelling said silica source in the presence of a strong mineral acid, the silica concentration in said aqueous solution corresponds to a SiO /H O mole ratio of at least about 0.01 and said aqueous reaction mixture has a composition corresponding to about 0.3 to about 0.5 (K O+Na O)/SiO about 10 to about 30 SiO /Al O and about 15 to about 40 H O/(- Kgo'i'Nago).
- ling step is carried out at a pH below about 5.
Abstract
Crystalline zeolite L is prepared in high yields from reactive silica gels having chemical water contents in excess of about 4.5 weight percent. The reactive silicas are preferably prepared by gelling a selected silica source at a pH below about 5.
Description
United States Patent [191 Young [111 3,867,512 [451 Feb. 18,1975
[ METHOD OF PREPARING CRYSTALLINE L ZEOLITE [63] Continuation-impart of Ser. No. 856,830, Sept. 10,
1969, abandoned.
[52] US. Cl 423/329, 423/118, 423/328, 252/455.2
[51] Int. Cl. C0lb 33/26, COlb 33/28 [58] Field of Search 423/329, 330, 328, 118; 252/455 Z [56] References Cited UNITED STATES PATENTS 3,216,789 11/1965 Breck et al. 423/328 3,298,780 1/1967 Fleck 423/329 3,366,578 1/1968 Michalko 252/455 Z 3,484,194 12/1969 Hindin et al. 423/329 OTHER PUBLICATIONS Iler The Colloid Chemistry of Silica and Silicates, 1955, pages 139-140.
Primary Examiner-Edward Stern Attorney, Agent, or Firm-Lannas S. Henderson; Michael H. Laird; Richard C. Hartman [57] ABSTRACT Crystalline zeolite L is prepared in high yields from reactive silica gels having chemical water contents in excess of about 4.5 weight percent. The reactive silicas are preferably prepared by gelling a selected silica source at a pH below about 5.
4 Claims, No Drawings 1 METHOD OF PREPARING CRYSTALLINE L ZEOLITE This application is a continuation-in-part of my copending application Ser. No. 856,830, filed Sept. 10, l969, now abandoned.
BACKGROUND Numerous synthetic aluminosilicates have'been prepared from a variety of silica and alumina sourcesln U.S. Pat. No. 3,216,789, Breck et al. suggest the use of a variety of silicas including silicic acid, aqueous colloid silica sols, reactive amorphous solid silicas suchas Santocel, Cab-O-Sil," Hi-Sil, powdered Vycor glass, Quoso, etc., silica gels and silicic acid forproducing zeolite L. In other words, it is suggested that any silica considered suitable for preparing any synthetic aluminosilicate can be used to make zeolite-L. However, it has also been observed that the reactive forms of silica having very high surface areas, usually attributable to minute particle sizes, such as the fume silicas, pyrogenic silicas and precipitated silica sols are more readily converted to certain zeolites than are alternative silica sources.
All of these reactive silicas are considerably more expensive than several of the alternative forms and several possess characteristics which render their use in aqueous digestion systems undesirable. The very fine particle size silica hydrosols exemplified by Ludox described in U.S. Pat. No. 2,597,782 and 2,574,902 are prepared by exhaustive ion exchange of dilute sodium silicate solutions followed by carefully controlled concentration and stabilization. The resulting hydrosols are several times as costly as sodium silicate on an equivalent SiO basis. Most of the amorphous solid silicas are prepared from silica hydrosols and accordingly are even more expensive, as are the dry aerogels and flame blown silicas of which Cab-O-Sil is representative. Moreover, these aerogels and flame blown silicas are fluffy, submicron size powders having very low bulk densities which render their use in aqueous systems quite difficult since they tend to form nondispersible gelatinous mixtures.
It is, therefore, one object of this invention to provide a method for the preparation of zeolite-L. It is another object of this invention to provide a method for the preparation of zeolite-L from inexpensive readily available silica sources. It is yet another object of this invention to provide a method for the preparation of zeolite L which enables the more economic utilization of zeolite precursors. Another object is to improve conversion of reactants to crystalline zeolite-L.
In accordance with one embodiment of this invention crystalline zeolite-L is produced by reacting a silica gel having a chemical water content above about 4.5 weight percent with a source of alumina in an aqueous reaction medium having a composition expressed as oxide mole ratios of about 0.3 to about 1 K O/(K O Na O), about 0.3 to about 0.6 (K O+Na O)/SiO about to about 40 SiO /Al O and about to about 140 H O/(K O-FNa O), at a temperature and for a period of time sufficient to form crystalline zeolite-L.
In anotherv embodiment L-zeolite is formed in high yields by the reaction of an alumina source and a reactive silica gel formed by syneresis at a temperature above about 100? and a pH below about 8 sufficient to produce a gel having a chemical water content of at least about 4.5 weight percent. Even higher tempera tures on the order of 150F and above are preferred in this embodiment.
Such reactive silicagels can be prepared at temperatures of about 30 to about 250F and pH levels below about 8. Higher temperatures can be used if facility is provided for'maintaining pressure on the system. For convenience, temperatures below 250F are usually employed. However, suitable gels cannot be prepared at the higher pH levels and lower temperatures. Thus it is necessary to correlate the temperature and pH level at which the gel is produced in order to assure the resulting product will have a chemical water content of at least about 4.5 weight percenLHowever, silica gels having this characteristic can be prepared throughout this temperature range at the lower pH levels, i.e., below about 5, preferably below about 3.
This method is based on the discovery that silica gels containing at least about 4.5 weight percent water react with alumina sources to form zeolite-L much more readily and with higher efficiency than do other silicas. The silica gels formed at low pH below about 5 are presently preferred due to their superior activity in these systems. The superiority of these gels is unexpected since they are not superior Y zeolite precursors. In fact the use of low pH gels having high water levels often results in the production of no Y zeolite whatever. The results obtained with zeolite Y suggest that if any difference in reactivity or conversion level exists between the numerous alternative silica sources, it is that silicas prepared in less acidic media are more reactive. I have now discovered that, to the contrary, silica gels having high chemical water levels, and preferably those prepared in more acidic media, or alternatively at higher temperatures, are much more reactive for the formation of zeolite-L in the systems described herein.
The reactive silica gel, as formed, should have a relatively high chemical water content of at least about 4.5 weight percent. Such gels are much more reactive for the production of L zeolite than are available alternatives formed under conditions which result in lower chemical water levels. They are usually prepared at pH levels below about 8 under conditions sufficient to produce a producthaving a chemical water content in excess ofabout 4.5 weight percent.
Gelling temperature has a significant influence on chemical water content. Higher chemical water levels are obtained at higher temperatures. Similarly, chemical water level increases as the gelling pH is reduced. Thus, temperature and pH must be correlated to obtain a reactive silica.
For example, highly reactive gels cannot be obtained at apH of 8 at relatively low gelling temperatures, i.e., on the order of 40F. Higher gelling temperatures are required at these pH levels. However, reactive gels having chemical water levels in excess of 4.5 weight perinvestigations of the relative influence of temperature and pH indicate that the chemical water content of the gel usually follows the expression:
H O 4 0.0056 T 0.4 pH
wherein T is the gelling temperature in degrees Rakine. Other variables such as silica concentration effect the validity of this expression somewhat. Nevertheless, it does provide a means for correlating temperature and pH as a preliminary step to establishing optimum reaction conditions. The optimum conditions of temperature, pH and silica content can be easily determined experimentally by producing gels at several pH levels, temperatures and silica concentrations, determining the resultant chemical water content of the gel, and selecting the optimum conditions accordingly.
A simple procedure for determining chemical water content involves drying the gel at 110C for 16 hours to expel physically bound water and then determining weight loss of the dried gel upon heating at l,lC for 2 hours.
A variety of gel precursors can be employed to produce these materials. Exemplary of these are the alkali metal, alkaline earth metal and ammonium silicates and silicic acid. Silica concentration should correspond to a Si0,lH O mole ratio of at least about 0.005 in order to produce a relatively concentrated gel which can be easily separated from the aqueous phase. Lower silica concentration can be employed although they are not preferred due to handling difficulty and the need for unfeasibly long contact times. Somewhat higher equivalent SiO /H O ratios within a range of about 0.01 to about 0.1 are generally employed, the higher concentrations being preferred due to ease in handling and shorter gelling times.
Although a wide range of conditions can be employed to produce thesegels, it is more expedient to use relatively high silica 'concentrationsjand elevated solution temperatures, both of which contribute to gellation rate and gel reactivity. As a result, preferred solution temperaturesusually range from about 80 to about 200F. At these temperatures and concentration levels, stable gels can be formed in about minutes. Nevertheless the gels can be more easily handled and more readily separated and purified if syneresis is allowed to continue for longer periods of up to 20 minutes to about 2 hours.
An alternative procedure involves the acidification of a basic silicate or silicic acid in an aqueous medium at a pH of about 0 and then increasing the pH to a value in excess of about 5, and preferably less than about 3. The solution pH will raise slightly due to the neutralizing effect of the basic silicate. However, additional base can be added such as ammonium or alkali and alkaline earth metal hydroxides, carbonates and the like.
Essentially any acid which will neutralize the basic silicate can be employed in this step of the procedure. illustrative acids are the strong mineral acids such as sulfuric, hydrochloric, nitric and phosphoric and organic acids such as formic, acetic and the like.
Following the desired degree of aging, the silica gel is separated from the supernatant liquid and water washed to remove residual acid. The resulting gel can be employed directly in the preparation of the aluminosilicates hereinafter detailed with or without mild drying or calcination. However, additional improvement in the suitability of these gels as reactants in the production of zeolite-L can be achieved by calcination prior to contacting in the aluminosilicate reaction medium. Although calcination is not essential due to the enhanced activity of these materials post treatment at temperatures of about 400 to about l,800F, preferably above about 600F for about 30 minutes to about 2 hours serves to further increase reactivity. Obviously such thermal treatment will reduce the gel water content. Nevertheless I have found that the use of gels having high chemical water levels as such is not essential. The essential requirement appears to be the use of a gel that was formed under conditions which resulted in a high chemical water content even if some or all of the chemical water is later expelled by calcination.
The resulting silica source is contacted with a suitable alumina source in an aqueous medium having a composition expressed as oxide mole ratios of about 15 to about H O/( K O+Na O) from about 0.3 to about 0.6 (K O+Na O)/SiO from about 10 to about 40 SiO /AI O It has also been found that the presence of minor amounts of sodium in the metalaluminosilicate reaction mixture expedites the production of zeolite L particularly in the potassium form. Consequently, it is often desirable to employ sodium concentrations within the range of up to about 2 Na- 2 /K2 Although crystalline zeolite-L can be readily recovered from all reaction mixtures within the above described ranges, it has been observed that varying amounts of dissimilar byproducts are produced depending upon the particular reactant ratiosemployed. The resolution of such byproducts can be greatly reduced by employing reactant concentrations within the range of from about 10 to about 30 SiO /Al O about 15 to about 40 H O/(K O+Na O), and about 0.3 to about 0.5 (K O+Na O)SiO Essentially any form of reactive alumina can be employed in the preparation of zeolite-L by these methods. Illustrative of such alumina sources are alumina trihydrate, activated alumina, alkali metal aluminates, e.g., sodium aluminate, potassium aluminate, etc., gamma alumina, alumina containing clays such as kaolin and the like, potassium aluminate being presently preferred. When an alumina source other than potassium aluminate is employed, the required potassium concentration can be derived from potassium hydroxide or one or more ionizable potassium salts such as the sulfate, halides, nitrate carbonate, acetate, formate, citrate and the like.
The zeolite-L is prepared by dispersing the alumina, alkali and silica sources in water under any of a wide range of conditions. Reaction temperatures can range from 140 to about 280F. although temperatures of about 180 to 230F. are generally preferred due to reaction rate and system vapor pressure. Product crystals can be separated from the reaction medium by any suitable method such as filtration. Purification is easily accomplished by water washing and mild drying if preferred. Contact times are usually at least about 30 minutes and are generally within the range of about 1 to about 48 hours.
The following examples illustrate the concept of this invention and are not intended to be limiting thereof.
EXAMPLE 1 A 1050 ml portion of N-Brand" sodium silicate was diluted with 4000 ml of water to form a solution which was then added to 380 ml of 12 normal sulfuric acid. Immediately following admixture of the silicate and acid solutions, the pH was adjusted to 4.0 by the addition of normal ammonium hydroxide. The resulting system was allowed to stand for minutes at 75F. at which time the first signs of gelation became apparent. At that time, i.e., after 30 minutes, sufficient additional ammonium hydroxide was added to the system to increase the pH to 9.0, whereupon the system set into a firm gel. The resulting gel was water washed to remove acid and soluble salts and dried for 16 hours at 2l2F. The dried gel was then ground into particulate form through a 0.0l0-slotted screen.
EXAMPLE 2 A 2 I00 ml portion ofN-Brand sodium silicate was diluted with 8000 ml of water. The resulting solution was then added to an excess of sulfuric acid, 702 ml of 12 normal H 50 Immediately following the combina- EXAMPLES 5-9 These silicas and a sample of Ludox-HS silica sol were separately mixed with potassium aluminate and water in amounts sufficient to form a metalaluminosilicate reaction mixture having the following composition represented as oxide mole ratios: H O/K O 90; K- O/SiO 0.40; SiO /Al O 20. The slurries were aged in a pressure vessel under system vapor pressure at 240F for 68 hours. The respective products were filtered, water washed and dried at 220F for 16 hours. The relative percent crystallinities of the products'were determined by X-ray diffraction and comparison to a standard zeolite-L sample. These tion of the silicate and acid the pH of the resulting sys 20 values are listed in the Table.
Silica Source Product Chemical Relative Gelling SiO /H O Gelling Drying Water Wt.7z Ex.No. Gel pH Mole Ratio Temp. F Temp. F Wt. 7c Zeolite-L 5 Exp.l 4.0-9.0 0.024 75 2l2 3.97 74 6 EXP] 6.0-7.6 0.024 75 212 3.75 51 7 Exp.3 0-l.2 0.053 75 212 7.00 169 8 Exp.4 7.0 0.023 75 300 I06 9 Ludox 68" 180 "'total water content tem was adjusted to 6.0 by the addition of 15 normal ammonium hydroxide. The occurrence of gelation became apparent immediately upon the addition of the ammonium hydroxide after which the pH was adjusted further upwardly to 7.6 by the addition of ammonium hydroxide and the system was allowed to set a firm gel. The resulting gel was washed, dried and granulated as described in Example 1.
EXAMPLE 3 A 755 ml portion of N-Brand" sodium silicate was admixed with 970 ml of water to form a solution which was then added gradually to 432 ml of 12 normal sulfuric acid. The original pH of the solution was 0. However, after star ding for 48 hours to enable the system EXAMPLES l0-l 5 Six additional L-zeolite preparations were made using the procedures described above. The conditions employed and results obtained are illustrated in the following Table.
Gelling Conditions Chemical Relative Wt.% Ex. No. pH Slo /H 0 Temp.F Water, Wt.% Zeolite-L I0 7.6-7.9 0.024 75 3.96 27 l I 1.3-1.1 0.024 75 6.29 I51 12 2.6-2.4 0.024 75 5.31 143 I3 2.0-].9 0.024 75 5.07 165 I4 5.9-6.l 0.024 200 5.0l I l5 3. 3.7 0.020 200 6.22 I56 to set to a firm gel the pH had risen to a value of 1.2. I claim:
The resulting gel was washed, dried and granulated as described in Example I.
EXAMPLE 4 A 2100 ml portion ofN-Brand sodium silicate was diluted with 8400 ml of water and added gradually to 702 ml of 12 normal sulfuric acid. Immediately following the combination of the silicate and acid solutions the pH of the system was adjusted to 7.0 by the addition 1. In a method for the preparation of crystalline zeolite L wherein reactive silica is dispersed in an alkaline reagent to form an aqueous reaction mixture having a molar composition corresponding to about 0.3 to about 1 K O/(K O-l-Na O), about 0.3 to 0.6 (K O+Na O)/- SiO about l0 to 40 SiO /AI O and about l5 to I40 H O/(K O+Na O), and wherein said reaction mixture is digested at a temperature and for a period of time sufficient to produce a recoverable yield of zeolite L,
the improved method for increasing the rate of formation and/or yield of L zeolite, which comprises utilizing as said reactive silica a reactive silica gel prepare by gelling a silica source selected from the group consisting of alkali metal, akaline earth metal and ammonium silicates and silicic acid in an aqueous solution having a silica concentrate corresponding to a SiO /H O mole ratio of at least about 0.005 at a pH below about 8 and a temperature between about 30 and 250F, correlated with said pH to produce a reactive silica gel containing at least about 4.5 weight percent of chemical water.
2. The method of claim 1 wherein said reactive silica gel is formed by gelling said silica source in the presence of a strong mineral acid, the silica concentration in said aqueous solution corresponds to a SiO /H O mole ratio of at least about 0.01 and said aqueous reaction mixture has a composition corresponding to about 0.3 to about 0.5 (K O+Na O)/SiO about 10 to about 30 SiO /Al O and about 15 to about 40 H O/(- Kgo'i'Nago).
ling step is carried out at a pH below about 5.
Claims (4)
1. IN A METHOD FOR THE PREPARATION OF CRYSTALLINE ZEOLITE L WHEREIN REACTIVE SILICA IS DISPERSED IN AN ALKALINE REAGENT TO FORM AN AQUEOUS REACTION MIXTURE HAVING A MOLAR COMPOSITION CORRESPONDING TO ABOUT 0.3 TO ABOUT 1 K2O (K2O+NA2O), ABOUT 0.3 TO 0.6 (K2O+NA2O) SIO2, ABOUT 10 TO 40 SIO2 AL2O3, AND ABOUT 15 TO 140 H2O (K2O+NA2O), AND WHEREIN SAID REACTION MIXTURE IS DIGESTED AT A TEMPEATURE AND FOR A PERIOD OF TIME SUFFICIENT TO PRODUCE A RECOVERABLE YIELD OF ZEOLITE L, THE IMPROVED METHOD FOR INCREASING THE RATE OF FORMATION AND OR YIELD OF L ZEOLITE, WHICH COMPRISES UTILIZING AS SAID REACTIVE SILICA A REACTIVE SILICA GEL PREPARE BY GELLING A SILICA SOURCE SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL, ALKALINE EARTH METAL AND AMMONIUM SILICATES AND SILICIC ACID IN AN AQUEOUS SOLUTION HAVING A SILICA CONCENTRATE CORRESPONDING TO A SIO2 H2O MOLE RATIO OF ABOUT LEAST ABOUT 0.005 AT A PH BELOW ABOUT 8 AND A TEMPERATURE BETWEN ABOUT 30* AND 250*F, CORRELATED WITH SAID PH TO PRODUCE A REACTIVE SILICA GEL CONTAINING AT LEAST ABOUT 4.5 WEIGHT PERCENT OF CHEMICAL WATER.
2. The method of claim 1 wherein said reactive silica gel is formed by gelling said silica source in the presence of a strong mineral acid, the silica concentration in said aqueous solution corresponds to a SiO2/H2O mole ratio of at least about 0.01, and said aqueous reaction mixture has a composition corresponding to about 0.3 to about 0.5 (K2O+Na2O)/SiO2, about 10 to about 30 SiO2/Al2O3, and about 15 to about 40 H2O/(K2O+Na2O).
3. The method of claim 1 wherein said silica source is selected from sodium and potassium silicates, said alumina source is potassium aluminate, and said silica gel containing at least about 4.5 weight percent chemical water is formed by gelling said silica source in the presence of a strong mineral acid.
4. A method as defined in claim 3 wherein said gelling step is carried out at a pH below about 5.
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EP0096479A1 (en) * | 1982-05-14 | 1983-12-21 | Exxon Research And Engineering Company | Improved zeolite L |
EP0104800A1 (en) * | 1982-09-07 | 1984-04-04 | The British Petroleum Company p.l.c. | Improved method of preparing crystalline aluminosilicates |
US4448891A (en) * | 1982-09-28 | 1984-05-15 | Exxon Research & Engineering Co. | Zeolite L catalyst for reforming |
EP0109199A1 (en) * | 1982-10-18 | 1984-05-23 | Tosoh Corporation | Process for preparation of L type zeolites |
EP0142349A2 (en) * | 1983-11-10 | 1985-05-22 | Exxon Research And Engineering Company | Stoichiometric process for preparing a zeolite of the L type |
EP0142351A2 (en) * | 1983-11-10 | 1985-05-22 | Exxon Research And Engineering Company | Method of preparing an improved catalyst |
US4552731A (en) * | 1983-11-10 | 1985-11-12 | Exxon Research And Engineering Co. | Process for preparing crystalline zeolite composition ERC-2 |
US4554146A (en) * | 1983-11-10 | 1985-11-19 | Exxon Research And Engineering Co. | Process for preparing a zeolite of the L type using organic templates |
US4593133A (en) * | 1982-05-14 | 1986-06-03 | Exxon Research & Engineering Co. | Zeolite L |
US4595668A (en) * | 1983-11-10 | 1986-06-17 | Exxon Research And Engineering Co. | Bound zeolite catalyst |
US4595670A (en) * | 1983-11-10 | 1986-06-17 | Exxon Research And Engineering Co. | Zeolite catalyst |
US4657748A (en) * | 1985-03-18 | 1987-04-14 | Exxon Research And Engineering Company | Crystalline zeolite (ECR-1) and process for preparing it |
US4657749A (en) * | 1983-11-10 | 1987-04-14 | Exxon Research And Engineering Company | Stoichiometric process for preparing a zeolite of the L type |
EP0323893A2 (en) * | 1988-01-04 | 1989-07-12 | Exxon Chemical Patents Inc. | Zeolite L |
US4888105A (en) * | 1988-02-16 | 1989-12-19 | Mobil Oil Corporation | Process for the dehydrocyclization of acyclic hydrocarbons and catalyst composition therefor |
US4925819A (en) * | 1983-11-10 | 1990-05-15 | Exxon Research & Engineering Company | Method of regenerating a deactivated catalyst |
USRE33323E (en) * | 1984-12-07 | 1990-09-04 | Exxon Research & Engineering Company | Reforming process for enhanced benzene yield |
US4956166A (en) * | 1987-04-22 | 1990-09-11 | Exxon Chemical Patents, Inc. | Zeolite L synthesis |
US4987109A (en) * | 1988-10-19 | 1991-01-22 | Exxon Chemical Patents Inc. | Zeolites for reforming catalysts |
US5017353A (en) * | 1983-11-10 | 1991-05-21 | Exxon Research And Engineering Co. | Recycled zeolite L preparation |
US5152884A (en) * | 1988-10-19 | 1992-10-06 | Exxon Chemicals Patents Inc. | Zeolites for reforming catalysts |
US5242675A (en) * | 1985-10-15 | 1993-09-07 | Exxon Research & Engineering Company | Zeolite L |
US5275800A (en) * | 1992-12-30 | 1994-01-04 | Aluminum Company Of America | Crystalline zeolites and method of preparation from amorphous silica particles |
US5330736A (en) * | 1992-12-07 | 1994-07-19 | W. R. Grace & Co.-Conn. | Zeolite L synthesis and resulting product |
US5486498A (en) * | 1986-10-14 | 1996-01-23 | Exxon Research & Engineering Company | Zeolite L |
US5670130A (en) * | 1989-08-09 | 1997-09-23 | Exxon Chemical Patents Inc. (Ecpi) | Zeolite L preparation |
US5855863A (en) * | 1988-01-19 | 1999-01-05 | Exxon Chemical Patents Inc. | Zeolite L preparation |
US5919721A (en) * | 1991-09-30 | 1999-07-06 | Exxon Chemical Patents Inc | Microfiltration of zeolites |
US6258256B1 (en) | 1994-01-04 | 2001-07-10 | Chevron Phillips Chemical Company Lp | Cracking processes |
US6419986B1 (en) | 1997-01-10 | 2002-07-16 | Chevron Phillips Chemical Company Ip | Method for removing reactive metal from a reactor system |
US6548030B2 (en) | 1991-03-08 | 2003-04-15 | Chevron Phillips Chemical Company Lp | Apparatus for hydrocarbon processing |
US6602483B2 (en) | 1994-01-04 | 2003-08-05 | Chevron Phillips Chemical Company Lp | Increasing production in hydrocarbon conversion processes |
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FR3090616A1 (en) | 2018-12-21 | 2020-06-26 | IFP Energies Nouvelles | Process for the preparation of an LTL structural type zeolite |
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US4593133A (en) * | 1982-05-14 | 1986-06-03 | Exxon Research & Engineering Co. | Zeolite L |
EP0096479A1 (en) * | 1982-05-14 | 1983-12-21 | Exxon Research And Engineering Company | Improved zeolite L |
US4701315A (en) * | 1982-05-14 | 1987-10-20 | Exxon Research & Engineering Co. | Zeolite L and process for its preparation |
US4544539A (en) * | 1982-05-14 | 1985-10-01 | Exxon Research & Engineering Co. | Zeolite L with cylindrical morphology |
EP0104800A1 (en) * | 1982-09-07 | 1984-04-04 | The British Petroleum Company p.l.c. | Improved method of preparing crystalline aluminosilicates |
US4448891A (en) * | 1982-09-28 | 1984-05-15 | Exxon Research & Engineering Co. | Zeolite L catalyst for reforming |
EP0109199A1 (en) * | 1982-10-18 | 1984-05-23 | Tosoh Corporation | Process for preparation of L type zeolites |
US4925819A (en) * | 1983-11-10 | 1990-05-15 | Exxon Research & Engineering Company | Method of regenerating a deactivated catalyst |
US5017353A (en) * | 1983-11-10 | 1991-05-21 | Exxon Research And Engineering Co. | Recycled zeolite L preparation |
US4552731A (en) * | 1983-11-10 | 1985-11-12 | Exxon Research And Engineering Co. | Process for preparing crystalline zeolite composition ERC-2 |
US4595668A (en) * | 1983-11-10 | 1986-06-17 | Exxon Research And Engineering Co. | Bound zeolite catalyst |
US4595670A (en) * | 1983-11-10 | 1986-06-17 | Exxon Research And Engineering Co. | Zeolite catalyst |
US4554146A (en) * | 1983-11-10 | 1985-11-19 | Exxon Research And Engineering Co. | Process for preparing a zeolite of the L type using organic templates |
US4657749A (en) * | 1983-11-10 | 1987-04-14 | Exxon Research And Engineering Company | Stoichiometric process for preparing a zeolite of the L type |
EP0142351A2 (en) * | 1983-11-10 | 1985-05-22 | Exxon Research And Engineering Company | Method of preparing an improved catalyst |
EP0142349A3 (en) * | 1983-11-10 | 1987-11-19 | Exxon Research And Engineering Company | Stoichiometric process for preparing a zeolite of the l type |
EP0142351A3 (en) * | 1983-11-10 | 1988-07-13 | Exxon Research And Engineering Company | Method of preparing an improved catalyst |
EP0142349A2 (en) * | 1983-11-10 | 1985-05-22 | Exxon Research And Engineering Company | Stoichiometric process for preparing a zeolite of the L type |
USRE33323E (en) * | 1984-12-07 | 1990-09-04 | Exxon Research & Engineering Company | Reforming process for enhanced benzene yield |
US4657748A (en) * | 1985-03-18 | 1987-04-14 | Exxon Research And Engineering Company | Crystalline zeolite (ECR-1) and process for preparing it |
US5396009A (en) * | 1985-10-15 | 1995-03-07 | Exxon Research & Engineering | Zeolite L |
US5242675A (en) * | 1985-10-15 | 1993-09-07 | Exxon Research & Engineering Company | Zeolite L |
US5486498A (en) * | 1986-10-14 | 1996-01-23 | Exxon Research & Engineering Company | Zeolite L |
US4956166A (en) * | 1987-04-22 | 1990-09-11 | Exxon Chemical Patents, Inc. | Zeolite L synthesis |
EP0323893A2 (en) * | 1988-01-04 | 1989-07-12 | Exxon Chemical Patents Inc. | Zeolite L |
EP0323893A3 (en) * | 1988-01-04 | 1990-03-21 | Exxon Chemical Patents Inc. | Zeolite l |
US5855863A (en) * | 1988-01-19 | 1999-01-05 | Exxon Chemical Patents Inc. | Zeolite L preparation |
US4888105A (en) * | 1988-02-16 | 1989-12-19 | Mobil Oil Corporation | Process for the dehydrocyclization of acyclic hydrocarbons and catalyst composition therefor |
US5152884A (en) * | 1988-10-19 | 1992-10-06 | Exxon Chemicals Patents Inc. | Zeolites for reforming catalysts |
US4987109A (en) * | 1988-10-19 | 1991-01-22 | Exxon Chemical Patents Inc. | Zeolites for reforming catalysts |
US5670130A (en) * | 1989-08-09 | 1997-09-23 | Exxon Chemical Patents Inc. (Ecpi) | Zeolite L preparation |
US6548030B2 (en) | 1991-03-08 | 2003-04-15 | Chevron Phillips Chemical Company Lp | Apparatus for hydrocarbon processing |
US5919721A (en) * | 1991-09-30 | 1999-07-06 | Exxon Chemical Patents Inc | Microfiltration of zeolites |
US5330736A (en) * | 1992-12-07 | 1994-07-19 | W. R. Grace & Co.-Conn. | Zeolite L synthesis and resulting product |
US5275800A (en) * | 1992-12-30 | 1994-01-04 | Aluminum Company Of America | Crystalline zeolites and method of preparation from amorphous silica particles |
US6258256B1 (en) | 1994-01-04 | 2001-07-10 | Chevron Phillips Chemical Company Lp | Cracking processes |
US6602483B2 (en) | 1994-01-04 | 2003-08-05 | Chevron Phillips Chemical Company Lp | Increasing production in hydrocarbon conversion processes |
US6419986B1 (en) | 1997-01-10 | 2002-07-16 | Chevron Phillips Chemical Company Ip | Method for removing reactive metal from a reactor system |
US6551660B2 (en) | 1997-01-10 | 2003-04-22 | Chevron Phillips Chemical Company Lp | Method for removing reactive metal from a reactor system |
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US9573122B2 (en) | 2014-08-29 | 2017-02-21 | Chevron U.S.A. Inc. | Small crystal LTL framework type zeolites |
FR3090616A1 (en) | 2018-12-21 | 2020-06-26 | IFP Energies Nouvelles | Process for the preparation of an LTL structural type zeolite |
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